Modem telecommunications is frequently carried out over public and private networks comprising a series of points or nodes interconnected by communication paths. Data enters and leaves the network through these nodes. Private networks are often used by businesses and other enterprises to facilitate data and resource sharing and data communication (e.g., electronic-mail and file transferring services) among employees. Local telephone companies (also referred to as local exchange carriers or Public Switched Telephone Networks, (PSTNs)) and long distance service providers (also referred to as inter-exchange carriers) are examples of public networks.
Traditional PSTNs or “legacy” networks are often referred to as Circuit Switched Networks (CSNs) because they utilize circuit switching, i.e., a type of switching in which the communication circuit (or path) for a particular call is dedicated to the call participants. Legacy networks are currently being replaced by packet-switched networks. Packet-switching is a method of data transport that uses relatively small units of data called “packets” to route data through the network based on a destination address contained within each data packet.
Public and private networks carry many types of data including voice and other media (e.g., video data). Current trends in public networks are toward “converged” communications networks, which are networks in which audio and video data are carried using the same method of transport as data applications such as Internet traffic. Increasingly, this method of transport is packet-switched rather than circuit-based.
However, converged communications networks must cooperate with legacy, circuit-switched networks. In general, users of different networks need to send voice and other media (generally referred to herein as “data”) to each other. Media gateways can be used for this purpose.
Both the Internet Engineering Task Force (IETF) and the International Telecommunications Unit (ITU) standards bodies have recognized the need for a physically and logically decomposed media gateway architecture in which a relatively intelligent media gateway controller (functioning as a “master” device) controls a relatively unintelligent media gateway (acting as a “slave” device). The media gateway acts as a transcoder between networks. A media gateway and a media gateway controller communicate with each other through a control protocol. The IETF Megaco Working Group and ITU SG16 jointly developed a Megaco/H.248 protocol for this purpose.